This month marks three years of marriage for me. I now know much more about my husband than I thought I could when we first met. We have settled into comfortable patterns of communicating. I know which buttons to push if I want to start a fight. I know how to encourage him, and a word or touch from him can change the course of my day.

Part of me looks forward to, say, our thirtieth anniversary, when we will have been through much more together and can reflect on lessons learned, challenges overcome, children raised; when we can offer our experiences to couples starting out together.

For now, I offer three points to consider about marriage. Whether you are searching, dating, engaged, or newly married, here is some truth about your spouse (current or future).

#1: Your Spouse is Human

In Song of Solomon, we see two starry-eyed lovers, thinking: No love is like ours; no one understands the depths of our love for one another. I remember that feeling. I was blissfully confident that any trial which dared to cross the path of my fiancé and me would be obliterated by our good sense, good communication and earnest devotion to one another. Such positive energy carried us far. But sometimes you need more.

Your beloved is only human. Sooner or later, you'll have to allow him or her that much. Being human means that your spouse will get sick, possibly at a time least convenient for you. He or she will honestly forget things, even things that you personally felt were too important to forget. You will need to forgive – even when it is not a matter of sin, but merely inconvenience or bad timing.

One of my first marital disappointments came from my expectation that we would retire together each night. As it turned out, my husband liked to work on his computer well after my bedtime. If he were to go to bed "early" with me, he would miss out on a productive, creative part of his day. If I tried to stay up "late" with him, I found it impossible to get up for work the next morning. At first I felt this as a loss. I had to surrender my expectation of sharing those dozing-off moments, and focus on our waking hours together. More importantly, I had to recognize that my spouse's sleep patterns were not "wrong," just different from mine.

I asked another couple, also married three years, what advice they would give to the engaged. They said, "learn how to fight!" You will disagree, but you can do so in a way that preserves love and respect. According to smartmarriages.com, researchers who have studied married couples over many years found that all couples have the same number of disagreements, over the same issues – finances, children, sex, housework, in-laws and time – but the factor that distinguishes successful couples is how they fight. Surrendering certain expectations and offering grace in light of differences go a long way in keeping love and respect alive.

#2: Your Spouse is a Sinner (And So Are You)

Everyone is a sinner. Some people don't offend our sensibilities as readily as others. When you date and marry someone, his or her sinful nature is not the first thing on your mind. You think of all the good qualities about your beloved, and even put your hope in the idea that those good qualities will do you good, make you better and solve some of your problems. As you grow in intimacy or simply share in the mundane, you will encounter the evil that lurks in the human heart.

One friend remarked that being married to the man of her dreams opened her eyes to how sinful her own heart was. If she couldn't love this great guy unconditionally, selflessly, could she love anyone? A fundamental reality in life is that we are all sinful; we cannot love perfectly in our own strength. This leads us to the glorious truth of Christ's atoning death, which is the only redemption acceptable to a righteous God. He took our sin, and in return He offers His righteousness. When God gives you His Spirit, love becomes possible. It's very good news. This side of heaven, we are still prone to sin – but in marriage, we have the opportunity to minister grace to one another in the deepest ways – and to receive grace.

Another observation, from older married Christian women, is that God allowed their husbands to "fail" them in order to graciously prevent them from idolizing their husbands. This is true for men, as well: a husband may look to his wife for validation or emotional support, but if he sometimes gets selfishness or silence instead, he may actually come closer to God, who is the real source of strength and purpose. Each time your spouse falls short, it can be your blessed reminder that God is the only perfect Lover. When God "fills your cup," you will be closer to your spouse, able to love without demands or prerequisites.

#3: You and Your Spouse Are One Flesh

Genesis 2:24 says: "for this reason a man will leave his father and mother and be united to his wife, and they will become one flesh." There are ways in which the "one flesh" reality is a mystery, and I would do no justice to it if I tried to put it into words. It's something that occurs when you first come together, and it only deepens with time. It's part of why I look forward to my 30th wedding anniversary. It's about subordinating all other relationships, even your parents, and making their needs and wishes secondary to your spouse's. (Of course, you must obey Scripture above your spouse – if they happen to contradict.)

At our wedding, Matthew 19:6 was pronounced, where Christ says: "So they are no longer two, but one. Therefore what God has joined together, let man not separate."

Recently that verse echoed in my head, followed by the phrase: "this means you!" I had always envisioned some stranger trying to interrupt marriages, but separation tends to happen more subtly – it could even start with me. Satan would love to entice me to blame my spouse for any and all conflict, to wish away the foundation we have built together, and to harden my heart against the beautiful intimacy that God has ordained. No matter how I feel on a given day, it is essential to remember that God has made us one flesh – a Truth bigger than us – and to open myself to the wonderful work He can do in our lives.

In his book Devotions for a Sacred Marriage, Gary Thomas wrote, "People who flit from relationships to relationship as their infatuations lead them aren't really happy; they're desperate – and they'll never find what they're looking for as they allow their desperation to bury potential life partners. There is no perfect "soul mate." … There will be only sinner after sinner after sinner. But when you learn to accept and love one particular sinner over several decades, you can slowly build an alliance and intimacy that nothing else can match."